Air conditioning apparatus

ABSTRACT

A supercooling heat exchanger of an air conditioning apparatus is configured to exchange heat between a high-pressure refrigerant and a low-pressure refrigerant. The supercooling heat exchanger is divided into first and second heat exchangers. One of the first and second heat exchangers is disposed so that the high-pressure refrigerant and the low-pressure refrigerant flow countercurrent to each other. The other of the first and second heat exchangers is disposed so that the high-pressure refrigerant and the low-pressure refrigerant flow parallel to each other. Preferably, both heat exchangers have a high-pressure liquid refrigerant pipe that is wound around the external periphery of a low-pressure refrigerant suction pipe. The heat exchangers are thereby reduced in size.

TECHNICAL FIELD

The present invention relates to an air conditioning apparatus that usesa supercooling heat exchanger.

BACKGROUND ART

FIG. 4 shows a configuration of an air conditioning apparatus that usesa conventional supercooling heat exchanger.

In this air conditioning apparatus, a compressor 1, a four-way switchingvalve 2, an outdoor-side heat exchanger 3 that functions as a condenserduring the cooling operation and as an evaporator during the heatingoperation, a heating expansion valve 4, a receiver 5, a coolingexpansion valve 6, an indoor-side heat exchanger 8 that functions as anevaporator during the cooling operation and as a condenser during theheating operation, and other components are connected sequentially viathe four-way switching valve 2, thereby constituting a refrigeratingcycle for air conditioning as is shown in the drawing.

The switching operation of the four-way switching valve 2 allows arefrigerant to be reversibly circulated in the direction shown by solidarrows in the drawing during the cooling operation, and in the directionshown by dashed arrows in the drawing during the heating operation,thereby resulting in cooling and heating, respectively.

The outdoor-side heat exchanger 3 and the indoor-side heat exchanger 8are both configured to include numerous refrigerant paths. Therefore,even if the capacity of the flow divider portion to distribute therefrigerant is improved to a maximum, it is difficult to distribute therefrigerant evenly throughout the refrigerant paths.

In view of this, when the outdoor-side heat exchanger 3 or theindoor-side heat exchanger 8 functions as the evaporator, the amount ofpressure reduction in the heating expansion valve 4 or cooling expansionvalve 6 is appropriately set so that the refrigerant of the exit side ofthe outdoor-side heat exchanger 3 or the indoor-side heat exchanger 8 isin appropriately humidified condition. Thus, maximum performance as theevaporator can be guaranteed even if, for example, the refrigerantdrifts into the outdoor-side heat exchanger 3 or the indoor-side heatexchanger 8, and therefore the evaporator can be made as compact aspossible.

The performance of the evaporator can be further improved by removingthe refrigerant supercooling of the exit side of the condenser,increasing the difference in enthalpy of the evaporator side to reducecirculating volume, and reducing the pressure loss on the evaporatorside. This is accomplished by providing a liquid-gas heat exchanger 13having a double pipe structure, composed of a low-pressure refrigerantsuction pipe 14 as an inner pipe and a high-pressure liquid refrigerantpipe 15 as an outer pipe, as a supercooling heat exchanger.

In this liquid-gas heat exchanger 13, e.g., the flow rate of therefrigerant, the length of the double pipes, the inside diameter of theouter pipe, and the outside diameter of the inner pipe are set in apredetermined manner appropriately.

As the liquid-gas heat exchanger 13 is provided in this manner, therefrigerant of the exit side of the evaporator is superheated, backflowinto the compressor 1 can be prevented, the refrigerant of the exit sideof the condenser is supercooled, and the difference in enthalpy of theevaporator side can be increased to reduce circulating volume.Therefore, the pressure loss can also be reduced, and the evaporator 8(or the evaporator 3) can be made even more compact (see Patent Document1 as an example).

[Patent Document 1]

Japanese Laid-open Patent Publication No. 5-332641 (Specification pg.1-5, FIGS. 1-5)

DISCLOSURE OF THE INVENTION <Problems the Invention is Intended toSolve>

However, a supercooling heat exchanger in which heat is exchangedbetween a high-pressure refrigerant and a low-pressure refrigerant asdescribed above has problems in that since the refrigerant flows inopposite directions during cooling and heating, the flows are parallelin either of the operating modes, and heat exchange is less efficient.For example, in the case shown in FIG. 4, the flows are countercurrentto each other during cooling and are parallel to each other duringheating, causing heat exchange to be less efficient.

The present invention was designed in order to resolve such problems,and an object thereof is to provide an air conditioning apparatuscomprising a supercooling heat exchanger for exchanging heat between alow-pressure refrigerant and a high-pressure refrigerant, wherein thesupercooling heat exchanger is divided into a first heat exchanger and asecond heat exchanger, either one of these heat exchangers is disposedso that the high-pressure refrigerant and the low-pressure refrigerantflow countercurrent to each other, and the other heat exchanger isdisposed so that the high-pressure refrigerant and the low-pressurerefrigerant flow parallel to each other, whereby the above-describedproblems with conventional practice are appropriately resolved.

<Means for Solving These Problems>

To achieve these objects, the present invention is configured with thefollowing means of solving these problems.

(1) Invention of a First Aspect

The means for solving the problems in accordance with this aspect is anair conditioning apparatus comprising a supercooling heat exchanger 13for exchanging heat between a low-pressure refrigerant and ahigh-pressure refrigerant, characterized in that: the supercooling heatexchanger 13 is divided into two first and second heat exchangers 13A,13B; either the first heat exchanger 13A or the second heat exchanger13B is disposed so that the high-pressure refrigerant and thelow-pressure refrigerant flow countercurrent to each other; and theother heat exchanger, i.e., either the second heat exchanger 13B or thefirst heat exchanger 13A, is disposed so that the high-pressurerefrigerant and the low-pressure refrigerant flow parallel to eachother.

The supercooling heat exchanger 13 for exchanging heat between ahigh-pressure refrigerant and a low-pressure refrigerant as previouslydescribed has problems in that since the refrigerants flow in oppositedirections during cooling and heating, the flows are parallel in eitherof the operating modes, and heat exchange is less efficient.

However, as described above, the supercooling heat exchanger 13 isdivided into two heat exchangers, i.e., the first heat exchanger 13A andthe second heat exchanger 13B, either the first heat exchanger 13A orthe second heat exchanger 13B is disposed so that the high-pressurerefrigerant and the low-pressure refrigerant flow countercurrent to eachother, and the other heat exchanger, i.e., either the second heatexchanger 13B or the first heat exchanger 13A is disposed so that thehigh-pressure refrigerant and the low-pressure refrigerant flow parallelto each other, whereby the supercooling heat exchanger 13 can maintainits heat exchange performance without variation even if the direction ofrefrigerant flow changes during cooling or heating.

(2) Invention of a Second Aspect

The means for solving the problems in accordance with this aspect ischaracterized in that, in the configuration of the means for solving theproblems in accordance with the invention of the first aspect, the firstand second heat exchangers 13A, 13B are both configured by winding ahigh-pressure liquid refrigerant pipe 15 around the external peripheryof a low-pressure refrigerant suction pipe 14.

Thus, when the first and second heat exchangers 13A, 13B are bothconfigured by winding the high-pressure liquid refrigerant pipe 15around the low-pressure refrigerant suction pipe 14, the capacity of theheat exchanger itself does not need to be increased, and thesupercooling heat exchangers 13A, 13B can be made as small as possible.

(3) Invention of a Third Aspect

The means for solving the problems in accordance with this aspect ischaracterized in that, in the configuration of the means for solving theproblems in accordance with the invention of the first aspect, the firstand second heat exchangers 13A, 13B are both configured by fitting ahigh-pressure liquid refrigerant pipe 15 around the external peripheryof a low-pressure refrigerant suction pipe 14 in a coaxial structure,wherein the high-pressure liquid refrigerant pipe 15 is larger indiameter than the low-pressure refrigerant suction pipe 14.

Thus, when the first and second supercooling heat exchangers 13A, 13Bboth have a double-pipe structure in which the high-pressure liquidrefrigerant pipe 15 is fitted coaxially over the low-pressurerefrigerant suction pipe 14, the structures of the supercooling heatexchangers 13A, 13B themselves are simplified.

EFFECT OF THE INVENTION

According to the present invention, as a result of the above, thesupercooling heat exchanger can maintain high heat exchange performanceeven when the flows of the refrigerants change direction during coolingand heating. As a result, the evaporator can be made more compact.

In this case, when the each heat exchanger is configured by winding ahigh-pressure liquid refrigerant pipe around a low-pressure refrigerantsuction pipe, the supercooling heat exchanger itself can be made assmall as possible.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a refrigeration circuit diagram showing the configuration ofan air conditioning apparatus according to Preferred Embodiment of thepresent invention;

FIG. 2 is an enlarged view showing the portion of the first and secondliquid-gas heat exchangers as relevant parts of the same apparatus;

FIG. 3 is an enlarged view showing a portion of the first and secondliquid-gas heat exchangers according to another embodiment of thepresent invention; and

FIG. 4 is a refrigerant circuit diagram showing the configuration of aconventional example of air conditioning apparatus.

DESCRIPTION OF THE REFERENCE SYMBOLS

-   1 Compressor-   2 Four-way switching valve-   3 Outdoor-side heat exchanger-   4, 6 Expansion valves-   5 Receiver-   8 Indoor-side heat exchanger-   13A First heat exchanger-   13B Second heat exchanger-   14 Low-pressure refrigerant suction pipe-   15 High-pressure liquid refrigerant pipe-   16 Muffler

BEST MODE FOR CARRYING OUT THE INVENTION

FIGS. 1 and 2 of the attached drawings show the configuration of theentirety and relevant parts of the refrigerant circuits in an airconditioning apparatus according to a preferred embodiment of thepresent invention.

First, as shown in FIG. 1, in the air conditioning apparatus of thisembodiment, a compressor 1, a four-way switching valve 2, anoutdoor-side heat exchanger 3 that functions as a condenser during thecooling operation and as an evaporator during the heating operation, aheating expansion valve 4, a receiver 5, a cooling expansion valve 6, anindoor-side heat exchanger 8 that functions as an evaporator during thecooling operation and as a condenser during the heating operation, andother components are connected sequentially via the four-way switchingvalve 2, thereby constituting a refrigerating cycle for air conditioningas shown in the drawing.

The switching operation of the four-way switching valve 2 allowsrefrigerant to be reversibly circulated in the direction shown by solidarrows in the diagram during the cooling operation, and in the directionshown by dashed arrows in the diagram during the heating operation,thereby resulting in cooling and heating, respectively.

A liquid-gas heat exchanger 13 is provided in this embodiment as well asthe case in FIG. 4 described previously. This liquid-gas heat exchanger13 comprises a low-pressure refrigerant suction pipe 14 and ahigh-pressure liquid refrigerant pipe 15, and is used as a supercoolingheat exchanger for exchanging heat between low-pressure refrigerant andhigh-pressure refrigerant.

As the liquid-gas heat exchanger 13 is provided in this manner,refrigerant of the exit side of the evaporator is superheated, backflowinto the compressor 1 can be prevented, the refrigerant of the exit sideof the condenser is supercooled, and the difference in enthalpy of theevaporator side can be increased to reduce refrigerant circulatingvolume, as was described previously. Therefore, pressure loss can alsobe reduced, and the evaporator (the indoor-side heat exchanger 8 duringcooling or the outdoor-side heat exchanger 3 during heating) can be madeas compact as possible.

However, in this embodiment, unlike in the case in FIG. 4 describedpreviously, the liquid-gas heat exchanger 13 is divided into twoliquid-gas heat exchangers, i.e., a first liquid-gas heat exchanger 13Aand a second liquid-gas heat exchanger 13B in which refrigerants flow inmutually opposite directions. The first heat exchanger 13A may, forexample, be disposed so that the high-pressure refrigerant andlow-pressure refrigerant flow countercurrent to each other, and thesecond heat exchanger 13B may be disposed so that the high-pressurerefrigerant and low-pressure refrigerant flow parallel to each other.

Therefore, with this configuration, the liquid-gas heat exchanger 13 canmaintain its performance without variation as shown in the diagrams,even when the refrigerant flow changes direction during cooling andheating. As a result, the refrigerant of the exit side of the condenseris supercooled without variation during heating, and the difference inenthalpy of the evaporator side can be increased to reduce thecirculating volume.

Moreover, the first and second liquid-gas heat exchangers 13A, 13B areboth configured so that the high-pressure liquid refrigerant pipe 15from the exit side of the condenser that is smaller in diameter than thelow-pressure refrigerant suction pipe 14 is wound in a helical structurein mutually opposite directions, for example, as shown in detail in FIG.2, around the external periphery of the low-pressure refrigerant suctionpipe 14. The existing low-pressure refrigerant suction pipe 14 leadsfrom the indoor-side heat exchanger (evaporator) 8 during cooling orfrom the outdoor-side heat exchanger (evaporator) 3 during heating backto the refrigerant suction inlet in the compressor 1 via the four-wayswitching valve 2. Therefore, the supercooling heat exchanger 13 itselfcan have a small capacity and can be made as small in size as possible.

The improvement in supercooling heat exchange efficiency is effective incontributing to making the evaporators themselves smaller and morecompact.

Furthermore, winding the high-pressure liquid refrigerant pipe 15 aroundthe existing low-pressure refrigerant suction pipe 14 as shown in FIG. 2makes it possible to inhibit increases in suctioned gas pressure loss,and to prevent the COP from decreasing.

The reference numeral 16 in FIG. 2 denotes a muffler for gas refrigerantin the low-pressure refrigerant suction pipe 14.

OTHER EMBODIMENTS

In the above embodiment, the divided first and second heat exchangers13A, 13B have a structure in which a high-pressure liquid refrigerantpipe 15 having a small diameter is helically wound around an existinglow-pressure refrigerant suction pipe 14 that goes from the four-wayswitching valve 2 to the refrigerant suction inlet of the compressor 1,as shown in FIG. 2. In another possible configuration, as shown in FIG.3, for example, the first and second heat exchangers 13A, 13B have adouble-pipe structure in which a high-pressure liquid refrigerant pipe15 larger in diameter than the low-pressure refrigerant suction pipe 14is fitted as a coaxial structure around the external periphery of thelow-pressure refrigerant suction pipe 14, and these pipes are disposedso that the refrigerant flows in mutually opposite directions.

Thus, as the first and second heat exchangers 13A, 13B for supercoolinghave a double-pipe structure in which the high-pressure liquidrefrigerant pipe 15 is fitted as a coaxial structure around thelow-pressure refrigerant suction pipe 14, the structure of thesupercooling heat exchanger itself is simplified.

INDUSTRIAL APPLICABILITY

The present invention can be widely utilized within the field of airconditioning apparatuses that use supercooling heat exchangers.

1. An air conditioning apparatus comprising: a supercooling heatexchanger configured to exchange heat between a low-pressure refrigerantand a high-pressure refrigerant, the supercooling heat exchanger beingdivided into first and second heat exchangers; one of the first andsecond heat exchangers being arranged such that the high-pressurerefrigerant and the low-pressure refrigerant flow countercurrent to eachother; and the other of the first and second heat exchangers beingarranged such that the high-pressure refrigerant and the low-pressurerefrigerant flow parallel to each other.
 2. The air conditioningapparatus according to claim 1, wherein each of the first and secondheat exchangers has a high-pressure liquid refrigerant pipe wound aroundan external periphery of a low-pressure refrigerant suction pipe.
 3. Theair conditioning apparatus according to claim 1, wherein each of thefirst and second heat exchangers a high-pressure liquid refrigerant pipefitted around an external periphery of a low-pressure refrigerantsuction pipe in a coaxial manner, the high-pressure liquid refrigerantpipe being larger in diameter than the low-pressure refrigerant suctionpipe.